Apparatus for ejecting stacks of articles from containers

ABSTRACT

Apparatus for automatically ejecting stacks of mail from the individual sorter boxes in an automatic mail sorting machine, includes a vertically movable platform below a magazine, and a horizontally movable pusher for ejecting stacks of mail off the platform. The pusher and platform are both controlled from a common drive shaft via a clutch bobbin controlling a single tension cord which provides a differential output. A bight in the cord is connected to the platform and another length of the cord extending horizontally is connected to the pusher. The platform is spring balanced and interlocks are provided so that when tension is applied to the cord, or the cord is released, a selected one of the two movable parts moves before the other in a controlled cycle.

Wood United States Patent [191 [111 3,820,669 [451 June 28,1974

1 1 APPARATUS FOR EJECTING STACKS OF ARTICLES FROM CONTAINERS [75] Inventor: David Wood, Clevedon, England [73] Assignee: Masson Scott Thrissell Engineering Limited, Bristol, England 22 Filed: Nov. 28, 1972' 21 Appl. No.: 309,987

[30] Foreign Application Priority Data Dec. 1, 1971 Great Britain 55685/71 [52] US. Cl. 214/8.5 SS, 221/268 [51] Int. Cl. B65g 59/06 [58] Field of Search... 214/85 F, 8.5 SS, 8.5 A;

[56] References Cited UNITED STATES PATENTS 3,409,150 11/1968 Voss 214/85 F 3,575,301 4/1971 Panissidi 214/1 BC Primary Examiner-Robert J. Spar Assistant Eraminer-George F. Abraham Attorney, Agent, or Firm- Young & Thompson [5 7] ABSTRACT Apparatus for automatically ejecting stacks of mail from the individual sorter boxes in an automatic mail sorting machine, includes a vertically movable platform below a magazine, and a horizontally movable pusher for ejecting stacks of mail off the platform. The pusher and platform are both controlled from a common drive shaft via a clutch bobbin controlling a single'tension cord which provides a differential output.

A bight in the cord is connected to the platform and another length of the cord extending horizontally is connected to the pusher. The platform is spring balanced and interlocks are provided so that when tension is applied to the cord, or the cord is released, a selected one of the two movable parts moves before the other in a controlled cycle.

7 Claims, 12 Drawing Figures 33 p 40 SW2 PATENTEDJUH28 w 3820 669 SHEET 3 BF 4 H642. 26 F/G.4f.

This invention relates to apparatus for ejecting a stack of generally flat articles such as postal mail, cards, orlike flat objects or sheets from a receptacle such as a magazine, container, or guide, and the invention is particularly though not exclusively applicable to a device for ejecting stacks of mail from the individual sorter destination boxes in an automatic mail sorting machine.

In such a machine there are usually a large number of individual boxes and the size and cost of each box is thus greatly multiplied-over the whole machine.

One important requirement in such machines is that the main sorting process should be able to proceed without interruption while stacks of mail are removed from individual boxes as they become full. It is also desirable that any selected box or boxes can be emptied as required, or that all boxes can be emptied substantially simultaneously when it is desired to clear the machine.

Broadly stated the present invention consists in apparatus for ejecting a stack of mail, cards, or like flat articles, from a receptacle, in a vertical magazine, box'or guide having a generally vertically movable platform or support on which the stack can be built up, a laterally movable pusher of substantial height arranged to transfer a stack off the platform, and means for controlling the movements of the platform and pusher from acommon power input, including a differential device having two output elements connected respectively to the pusher and the platform.

Preferably one output element is arranged to move the platform downwards, and the other output element is arranged to move the pusher in a direction to eject the stack, and the apparatus includes means for restraining the ejection movement of the pusher until the platform has moved downwards to a pre-selected positron.

The arrangement may be such that the differential output element connected to the platform tends to move the platform before the other output element moves the pusher.

In one particular convenient construction the differential device comprises a tension cord having a bight extending transversely to another section of the cord, the bight and the said section being connected one to the pusher and one to the platform.

The single power input may include a clutch providing a controlled input from a power source such as a driving shaft. g

The invention may be performed in various ways and one specific embodiment with a number of possible modifications will now be described by way of example with reference to the accompanying drawings, in which:

FIG. I is a diagrammatic side elevation partly in section of a magazine or destination box in a mail sorting machine, illustrating a movable platform and ejector pusher,

FIG. 2 is a diagrammatic rear view of the apparatus as seen in the direction of arrow II in FIG. 1,

FIG. 3 is a diagrammatic plan view of the vertical moving platform,

' FIGS. 4(a) to 4(/) are diagrams illustrating six stages in the movements of the components,

FIG. 5 is a simplified circuit diagram illustrating a typical control circuit for controlling the actuation of the mechanism,

FIG. 6 is a side elevation on anenlarged scale illustrating a modified form of pack-shearing device which may be incorporated, and

FIG. 7 is an end elevation of the: paclt shearing device of FIG. 6.

Referring first to FIG. 1 this illustrates an automatic ejector system for ejecting stacks of mail from a desti nation box in an automatic letter sorting machine. A large number of such destination boxes are arranged in rows at different levels and when each box is nearing the point of being full the ejector device is arranged to eject a stack onto a conveyor which transports the stack to an automatic bundling machine ready for despatch. The main sorting machine continues in operation uninterrupted during the emptying cycle and mail continues to be delivered vertically downwards into the sorter boxes, with each envelope lying generally horizontally in the stack.

The apparatus illustrated in FIG. 1 comprises a vertical sorter box or magazine 10, having front and rear walls 11, 12, and sidewalls 13; A vertically movable platform 14 is arranged to support a stack of mail 15 and is slidably mounted on a pair of vertical guide rods 16. The platform consists of a pair of parallel spaced plates 17 (see FIG. 3) each attached to a block 18 sliding on one of the guide rods 16, and the two blocks may be interconnected by a bridge (not shown) to ensure that both move together. The platform is urged upwardly by a pair of springs 20 connected to the blocks 18 and to fixed points on the framework of the apparatus. The spring rate is selected to correspond to the weight/height relationship (i.e., density) of average mixed postal mail within the territory in which the sorting machine is operating. In this way the level of the top letter or envelope in the stack 15 is maintained approximately constant as the height of the stack increases. It will be noted that as shown in FIG. 1 the level of the top of the stack 15 is somewhat above the level of the bottom edge of the front wall 11 which acts to retain the top part of the stack within the magazine. The height of the stack being ejected is thus controlled by the vertical interval between the wall 11 and the platform 14. The front wall 11 is pivotally mounted on a horizontal hinge axis 9, which incorporates a tension spring so arranged that the wall can pivot upwards as shown by the arrow 8 to allow for variations in the stacking angle which may be irregular at the top of the stack.

Ths stack of mail on the platform is ejected by a generally vertical pusher plate 25 attached to a block 26 which is slidably mounted on a horizontal guide rod 27. Normally the pusher plate 25 is positioned on the extreme left side of the stack as illustrated in FIG. I but when traversed to the right the greater part of'the stack of mail on the platform 14 is ejected onto the receiver plate 30. Any mail in excess of the predetermined height of the stack is retained by the front wall 11. This excess mail is supported temporarily by a rigid polished metal horizontal plate 31 attached to the upper end of the pusher plate 25. This support plate is additionally supported by an anti-friction bearing block 32, and

moves across below the sorter box 10 when the pusher wound onto a bobbin 34 which includes a coiled tensioning spring (not shown) and an electrically controlled clutch for coupling the bobbin when required to a rotary drive shaft 35 driven continuously by a main electric motor of the sorting machine and extending along a row of such destination sorter boxes. The tension cord 33 extends around a guide pulley 36 and has a bight 37 extending vertically upwards around a pulley 38 attached to the movable guide block 18. The other end of the bight passes around another stationary pulley 39 and extends horizontally around a further pulley 40 positioned at the front of the machine, the other end of the tension cord 33 being attached to the guide block 26 at the bottom edge of the pusher plate 25. A light tensator type return spring 41 attached to a cord 42 is provided to return the pusher plate 25 to the left hand position when the bobbin clutch 34 is deenergized.

The apparatus also includes locking rollers 43 attached to the underside of the platform 14 and bearing against the face of the pusher plate 25 to prevent the pusher plate moving to the right to eject a stack until the platform 14 has descended to its bottom position and the rollers are clear of the plate. Further locking rollers 44 are also provided to prevent the platform 14 rising until the pusher plate 25 has moved to its extreme right-hand eject position. These rollers 44 are attached to the rear of the pusher plate 25 near its lower end, and when the platform 14 is fully depressed the rollers can bear down on the top surface of the platform. Slots 45 in the platform guide blocks 18 allow the platform to pass vertically over the locking rollers 44 when the pusher plate is in its left hand position. In addition the apparatus includes a switch SW1 arranged to close when the platform 14 has moved downwards to the position indicated at 14 corresponding to a full magazine, and another switch SW2 arranged to open when the pusher plate 25 has moved to its extreme right-hand eject position.

It will be noted that the bight 37 in the tension cord 33 provides a 2:1 mechanical advantage for applying a downward pull on the platform 14, thus reducing the load requirement on the clutch in the bobbin 34.if the platform is pulled down before the weight of mail in the stack has caused the platform to descend naturally. The load resistance applied by the springs of the platform 14 on the tension cord 33 is considerably greater than the resistance applied by the pusher plate 25, in normal operation, so that when tension is applied to the cord 33 by the clutched bobbin 34 the cord will tend first to pull the pusher plate across to the right.

This being prevented by the interlock rollers 43 the cord will first pull down the platform, and only when the platform reaches its bottom position, and the interlock rollers 43 are freed, will the tension cord tend to move the pusher plate 25 to the right.

The electrical control circuit is illustrated diagrammatically in simplified form in FIG. 5. The electrically operated bobbin clutch is connected across the supply SS through relay contacts RLl/2 of a relay coil RLl arranged in parallel with the clutch, both being connected in series with the two limit switches SW1 (normally open) and SW2 (normally closed). Further relay contacts RL 1/] of the relay RLl are connected in parallel across the switch SW1 to act as a holding circuit, and a manual or automatic switch 48 is also connected in parallel with switch SW1. The clutch 34 is provided with a permanent low biassing voltage through an adjustable resistor 49, and the movement of the clutch bobbin is damped by a capacitor C connected across the clutch windings.

The sequence of movements is illustrated diagrammatically in FIGS. 4(a) to 4(/).

In normal operation the platform 14 descends progressively under the increasing weight of mail (the cord 33 being wound up onto the spring bobbin 34) until when the platform has reached its selected bottom position, as indicated at 14' in FIG. 1 and as shown in FIG. 4(a), signifying a full box. switch SW1 closes which operates relay RLI, closes contacts RL l/ l and RL 1/2, and the clutch is energised. With the platform 25 in its bottom position 14 the pusher plate 25 is free to move to the right and the engaged clutch winds in the cord 33 onto the bobbin and so pulls the pusher plate 25 to the right as shown in FIGS. 4(b) and 4(0) to eject the stack of mail 15. During this movement the locking rollers 44 prevent the platform ascending. When the pusher plate reaches its extreme right hand position switch SW2 opens and causes the clutch to disengage. With the locking rollers 44 clear of the platform the latter is then free to rise as shown in FIG. 4(d) under the influence of the tension springs 20 (which may incorporate a damping device) so unwinding the tension cord 33 from the bobbin 34. When'the platform reaches its uppermost position the pusher plate 25 is automatically drawn back to the left hand position by the tensator 41, as shown in FIG. 4(e), thus unwinding further cord from the bobbin. The cycle can then repeat as shown in FIG. 4(/').

If it is required to eject mail from a partly full box the switch 48 is closed by some other external actuating means, either automatic or manual, and as a result the clutch will be energised prematurely (i.e., the platform 14 is not in its bottom position). Since the pusher plate 25 is prevented from moving to the eject position except when the platform is in its lowermost position, the engagement of the clutch 34 will first cause the ,cord 33 and the bight 37 to pull down the platform 14 to its bottom position. Switch SW1 is effectively bypassed and its closure at this point has no effect since the clutch is already energised. When the platform 14 reaches its bottom position the pusher plate 25 is then free to traverse to the right, which is effected by continued winding of the cord onto the bobbin. At the end of the eject stroke switch SW2 opens, the clutch is de-energised, and the remainder of the cycle continues as described above.

In order to control the velocity of the return movements of the platform 14 and pusher plate 25 a rotary vane dashpot device can be incorporated in the clutch bobbin 34, thus applying a speed control on the return movement of both the platform and pusher plate.

The sorting machine may include manual or automatic, individual or joint, controls for actuating any one of the sorter box ejector mechanisms to clear a box when required, regardless of whether the box is partly or completely full, and if necessary all boxes can be emptied simultaneously, or all the boxes in each row on a row-by-row basis.

It will be noted that during normal running the boxes can be emptied whilst the normal letter sorting section of the machine is still in operation, further incoming mail being supported on the plate 31 while the pusher plate 25 is carrying out an eject movement.

In the arrangement described a light tension is maintained in the cord 33 while mail is filling the sorter box 10, and during restoring movements, by a combination of the spring and the-vane dashpot in the clutch bobbin 34. It has been found however that both these functions may be obtained by applying a small residual voltage to the clutch coil via the resistor 49 illustrated in FIG. 5.

FIGS. 6 and 7 illustrate an alternative pack-shearing device which may be employed in place of the pivoted front wall 11 of FIG. 1. This device is power-operated 6 small degree of friction in the vertical guide for the platform.

I claim:

and designed to reduce the tendency for the top items I of mail in the stack 15 to assume a partially ejected position when the main stack is ejected to the right.

A lever 72 is attached to a sleeve 73 pivotally mounted surrounding a constantly rotating slow speed shaft 74. The lower end of the lever supports a rubbercovered roller 75 attached to a pulley 76, and a rubber belt 77 drives the roller from another pulley 78 fixed to the shaft 74, the direction of rotation of the roller being indicated by arrow 79 in FIG. 6. The sleeve 73 is at .tached to a helical spring 80 whose other end is secured to an angularly adjustable fixed collar 81, the spring tending to urge the lever in the direction of arrow 82 downwards onto the top of the stack. The'lever 72 is normally located in an upright vertical position by a dog 83 engaging a dog 84 attached to a stationary boss 85, but the lever can move against the spring to an inclined position as shown in FIG. 6. In this Figure a stack 15 is being ejected, and if any items of mail such as those shown at 88 do not move uniformly with the main stack the contra-rotating roller 75 will drive them back to their original position below the main sorter box 10. It will be noted that if the resistance to movement of these mail items 88 increases, the pressure exerted by the roller 75 will also increase, thus providing a positive feed back effect. 7

In a further possible modification, instead of using a constant rate spring device for controlling the movement of the platform 14 such that the top of the stack of mail is at a constant height, the spring device may be designed with a rate such that the working height of mail in the stack tends to increase constantly with mail of the highest possible weight/thickness ratio likely to be encountered. An optical levelling system including a lamp and photo-cell combination is situated at the desired working level to sense the position of the uppermost letter in the stack. The signal derived is then applied via suitable logic circuitry to energise the clutch of the bobbin when the working level rises above the set limit. Conversely the clutch will be de-energised when the platform has been lowered sufficiently to restore the working level. When the clutch is deenergised, with the stack of mail on the platform, the platform is prevented from rising by an intentional 1. Apparatus for forming and ejecting a stack of flat articles, comprising a vertical magazine having an opening at its upper end through which said articles are fed into said magazine, two movable components namely a generally vertically movable platform on which the stack can be built up, and a laterally movable pusher of substantial height arranged to transfer a formed stack off said platform, means for controlling the movements of said platform and pusher including a common power member, a differential device having an input element connected to said power member and two output elements connected respectively to said pusher and said platform, at least one resilient return spring device, and interlock means acting between said pusher and said platform to restrain movement of one of said components until the other said component has moved to a predetermined position, and then to release said first component automatically for movement in response to the force exerted by said return spring device or the respective one of said differential output elements.

2. Apparatus according to claim 1, including further interlock means acting between said platform and said pusher to restrain movement of the other of said components until the first component has moved to a predetermined position.

3. Apparatus according to claim 1, in which one of said output elements is arranged to move said platform downwards, and the other output element is arranged to move said pusher horizontally in a direction to eject the stack, and said interlock means includes means for restraining the ejection movement of the pusher until the platform has moved downwards to a preselected position.

4. Apparatus according to claim .1, in which the resistive forces acting on said platform are greater than those acting on said pusher whereby the differential output element connected to said pusher tends to move the pusher before said other output element moves said platform.

5. Apparatus according to claim 1, including a clutch providing a controlled input from said power member to said input element of the differential device.

6. Apparatus according to claim 1, in which said differential device comprises a tension cord having a bight extending transversely to another section of the cord, the bight and the said section being connected one to said pusher and one to said platform.

7. Apparatus according to claim 6, in which one end of said tension cord is operatively connected to a resistent return spring device. 

1. Apparatus for forming and ejecting a stack of flat articles, comprising a vertical magazine having an opening at its upper end through which said articles are fed into said magazine, two movable components namely a generally vertically movable platform on which the stack can be built up, and a laterally movable pusher of substantial height arranged to transfer a formed stack off said platform, means for controlling the movements of said platform and pusher including a common power member, a differential device having an input element connected to said power member and two output elements connected respectively to said pusher and said platform, at least one resilient return spring device, and interlock means acting between said pusher and said platform to restrain movement of one of said components until the other said component has moved to a predetermined position, and then to release said first component automatically for movement in response to the force exerted by said return spring device or the respective one of said differential output elements.
 2. Apparatus according to claim 1, including further interlock means acting between said platform and said pusher to restrain movement of the other of said components until the first component has moved to a predetermined position.
 3. Apparatus according to claim 1, in which one of said output elements is arranged to move said platform downwards, and the other output element is arranged to move said pusher horizontally in a direction to eject the stack, and said interlock means includes means for restraining the ejection movement of the pusher until the platform has moved downwards to a preselected position.
 4. Apparatus according to claim 1, in which the resistive forces acting on said platform are greater than those acting on said pusher whereby the differential output element connected to said pusher tends to move the pusher before said other output element moves said platform.
 5. Apparatus according to claim 1, including a clutCh providing a controlled input from said power member to said input element of the differential device.
 6. Apparatus according to claim 1, in which said differential device comprises a tension cord having a bight extending transversely to another section of the cord, the bight and the said section being connected one to said pusher and one to said platform.
 7. Apparatus according to claim 6, in which one end of said tension cord is operatively connected to a resistent return spring device. 